Process for the preparation of 1,2-benzisothiazolin-3-ones

Abstract

A process for making a 2-alkylbenzisothiazolinone which comprises reacting a bisamide of formula in water or an organic liquid containing water with a bisulphite or bisulphite release agent to form a Bunte salt and converting the Bunte salt under alkaline conditions to 2-alkyl-BIT. R is alkyl. Preferred substituents R are butyl, hexyl, 2-ethylbutyl and 2-ethylhexyl.

What is claimed is:  
     
       1. A process for making BIT of formula 1                    
       which comprises reacting a bisamide of formula 5                    
       wherein, 
       R is cycloalkyl containing from 3 to 8 carbons atoms or C 1-20 -alkyl optionally substituted by phenyl;  
       X is halogen, nitro, alkoxy or nitrile;  
       n is 0 to 4; and  
       q is 0, 1, or 2  
       in water or an organic liquid containing water with metabisulphite.  
     
     
       2. A process as claimed in  claim 1 , wherein n is zero. 
     
     
       3. A process as claimed in  claim 1 , wherein R is C 1-12 -alkyl optionally substituted by phenyl. 
     
     
       4. A process as claimed in  claim 1 , wherein R is methyl, n-butyl, n-hexyl, n-octyl, 2-ethylbutyl, 2-ethyl-hexyl, i-hexyl or 2-phenylethyl. 
     
     
       5. A process as claimed in  claim 1  wherein, the organic liquid is methanol.